title: A conditional predictive p-value to compare a multinomial with an overdispersed multinomial in the analysis of T-cell populations.
abstract: Immunological experiments that record primary molecular sequences of T-cell receptors produce moderate to high-dimensional categorical data, some of which may be subject to extra-multinomial variation caused by technical constraints of cell-based assays. Motivated by such experiments in melanoma research, we develop a statistical procedure for testing the equality of two discrete populations, where one population delivers multinomial data and the other is subject to a specific form of overdispersion. The procedure computes a conditional-predictive p-value by splitting the data set into two, obtaining a predictive distribution for one piece given the other, and using the observed predictive ordinate to generate a p-value. The procedure has a simple interpretation, requires fewer modeling assumptions than would be required of a fully Bayesian analysis, and has reasonable operating characteristics as evidenced empirically and by asymptotic analysis.
authors.affiliation: Department of Statistics, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Qinglin
authors.initials: Q
authors.lastname: Pei
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Zuleger
authors.forename: Michael D
authors.initials: MD
authors.lastname: Macklin
authors.forename: Mark R
authors.initials: MR
authors.lastname: Albertini
authors.forename: Michael A
authors.initials: MA
authors.lastname: Newton
mesh_terms: D049109:Cell Proliferation; D022801:Complementarity Determining Regions / Q000235:genetics / Q000276:immunology*; D003627:Data Interpretation, Statistical; D006801:Humans; D015233:Models, Statistical; D009154:Mutation / Q000235:genetics / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D017422:Sequence Analysis, DNA; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D022801:Complementarity Determining Regions; D011948:Receptors, Antigen, T-Cell
keywords: Bayesian p-value; Dirichlet multinomial; Double overdispersion; Fisher's exact test; HPRT assay; Mass culture experiments; Molecular sequence data; T-cell receptor